This invention relates to a roll stand for bar and wire rod rolling mill, capable of being adapted to the rolling of bars and wire rods by a small number of housing block sets and carrying out maintenance work therefor easily, and having characteristics in a housing thereof.
There is a roll stand disclosed in Japanese Patent No. 2667043, as a related art example of a roll stand for bar and wire rod rolling mill. In this roll stand, a plane in which a rotary shaft of each groove roll exists and a plane in which a rotary shaft of a driving gear for each groove roll exists are parallel to each other along a pass line. The rotary shaft of each groove roll is mounted fixedly with a driven gear meshed with a relative driving gear. Namely, each groove roll is rotated by the rotation of a relative driving gear via a relative driven gear. Each groove roll has an eccentric shaft supporting the groove roll rotatably, and a clearance between the rolls can be regulated. A housing of this roll stand is of a three-piece structure.
The construction of this roll stand is shown in FIGS. 1-3. The roll stand shown in these drawings is of a four-roll type.
FIG. 1 is a perspective view showing an external appearance and a divided condition of the roll stand. A reference numeral 70 denotes an external appearance, and 80 denotes a divided condition of the roll stand, in which the roll stand is separated into three blocks 81, 82, 83. A reference numeral 1 denotes a groove roll, 3 denotes a driven gear, 2 denotes a driving gear, and 8 denotes a pass line. Referring to FIG. 1, a left side surface of the block 81 along the pass line and a right side surface of the block 82 along the pass line correspond to planes in which a rotary shaft of each groove rolls exist. Referring to FIG. 1, a left side surface of the block 82 along the pass line and a right side surface of the block 83 along the pass line correspond to planes in which the rotary shafts of the driving gears for the groove rolls exist.
FIG. 2 is a side view along the pass line showing the relation among a housing block, roll stand housing dividing positions, the groove rolls, driving gears and driven gears. Referring to FIG. 2, a pitch circle of the driving gear 2 of FIG. 1 is shown by a one-dot chain line 20, and that of the driven gear 3 of FIG. 1 fixed on the rotary shaft of each groove roll 1 is shown by a one-dot chain line 30. A point 61 denotes a center of rotation of the groove roll and driven gear, a point 62 denotes a center of rotation of the driving gear, and a point 63 denotes a center of rotation of the eccentric shaft 6. Referring to FIG. 2, the roll stand 80 is divided into the three blocks 81, 82, 83 from the side of a plane 72 by the plane 71 in which the axes of rotation of the four groove rolls 1 exist and by the plane 72 in which the axis of rotation of the driving gear 2 for each groove roll 1 exists. As shown in FIG. 2, the plane 72 is in a position which is parallel-spaced from the plane 71 along the pass line 8.
FIG. 3 is an enlarged view of an upper portion of FIG. 2. The eccentric shaft 6 and rotary shaft 7 are hatched. As shown in FIG. 3, the rotary shaft 7 of the groove roll is made hollow. In the hollow of the rotary shaft 7, the eccentric shaft 6 is supported rotatably with respect to the rotary shaft 7. A distance between the driving gear 2 and driven gear 3 can be changed in accordance with a rotation of the eccentric shaft 6. The reason resides in the following. The driving gear 2 is retained so as to be rotated in a predetermined position at all times. When the eccentric shaft 6 is rotated for the regulation (called xe2x80x9cparting regulationxe2x80x9d) of an inter-roll clearance, a center 61 of rotation (i.e. a center of rotation of the rotary shaft 7) of the driven gear 3 moves along an arc having as its center a center 63 of rotation of the eccentric shaft 6. When upper and lower rolls come closest to each other, the center 61 of rotation reaches a position 612. When they come apart most, it reaches a position 611. A parting regulation amount xcex1 corresponds to a distance between points 611 and 612.
Especially, FIG. 3 shows a condition in which the eccentric shaft 6 is in a top dead center (position closest to the driving gear) of the eccentric arc. This condition is also a condition in which the driven gear 3 has a central value of the partition regulation, and a distance between centers of the driving gear 2 and driven gear 3 is so maintained that the gears 2, 3 are correctly meshed with each other (standard pitch circles thereof contact each other). When an eccentric position of the eccentric shaft 6 deviates from the upper dead center, the distance between the centers of the driving gear 2 and driven gear 3 slightly increases. Due to the increase of the center distance, a backlash between the gears increases but this does not cause a problem in particular concerning the meshing of the gears. Accordingly, the parting regulation amount xcex1 can be changed.
A roll rotating mechanism including the driven gear 3 and the groove roll 1 are housed in the interior of the first block 81 which constitutes a cover for the groove roll, and the second block 82 which is a part between the plane 71 and plane 72. A driving mechanism including the driven gear 2 is housed in the interior of the second block 82 and the third block 83 which constitutes a cover for the driving mechanism. The replacement of the groove roll 1 is carried out with removing the first block, and the maintenance work for the driving mechanism with removing the third block 83.
In the roll stand having a housing of such a three-piece structure, it is necessary that the first block 81 and second blocks 82 be used in a 1:1 unit for the convenience of the engagement of an outer circumference of a seal for a neck portion of the groove roll 1 and a circumference of the rotary shaft of the roll, and that these blocks be kept in a set. Namely, the first blocks 81 and second block 82 out of different block sets cannot be combined and used together. Therefore, when only one set of first block 81 and second block 82 is available, a rolling operation cannot be carried out during the replacement of the groove roll 1. In order to carry out a rolling operation efficiently without stopping the same, it is necessary to have a large number of block sets of housing. Especially, these days, many types of small lots of products have been demanded, and a required number of block sets tends to increase more and more.
In order to prevent refuse and dust from entering the interior of the housing, it is necessary that the roll stand be kept with the three blocks in an assembled state. Therefore, a lot of space is required, and the handling of the roll stand becomes troublesome.
As described above, there is yet room for improvement in the related art roll stand with respect to the cost of manufacturing of the housing and the way of handling the same.
To solve the problems of reducing the cost and facilitating the handling of the housing of the related art roll stand for bar and wire rod rolling mill, the roll stand for bar and wire rod rolling mill according to the present invention has been made which is characterized in that a housing thereof is divided into two, i.e. a roll block and a driving block by a plane including a position in which a driving gear and a driven gear are meshed with each other or a position in the vicinity thereof. Namely, the present invention is a roll stand formed of a roll block including a groove roll, a driven gear fixed on a rotary shaft of the groove roll, an eccentric shaft supporting the groove roll rotatably thereon, and a housing in which these parts are incorporated; and a driving block including a driving gear, and a housing in which the driving gear is incorporated, a plane in which the roll block and driving block contact each other being parallel to a plane which includes the rotary shaft of the groove roll and a plane which includes a rotary shaft of the driving gear, and constituting a plane which includes meshed portions or their vicinity portions of the driving gear and driven gear which cross a pass line at right angles thereto. The driving gear and driven gear mentioned above are preferably spur gears or helical gears.